Hello all, I am wiriting here to look for help!!! I am running a mixed-model effect lmer() relating the total species richnees observed in one place with some landscape indicators depending on three positions at field scale (Boundary, edge, centre) nested to the location where the survey was conducted. The model follow the next instruction lmer(a~position*%naturalvegetation + position*P/A+ (1|location) However, running the model in this way it is not possible to compare position between them and I have to run orthogonal contrast for this porpouse. my data matrix has the following structure Richness Location %NV P/A Location 3 1 34.3 0,43 B 5 2 45.2 0.33 B 12 3 21.2 0.21 E 6 4 11.2 0.21 E .... .... 8 135 76.3 0.29 C How can I run the orthogonal contrast. Somebody now how tu run it and the necessary code. Excuse me because I am not an stadistic people. I am botanic.... Thanks! -- View this message in context: http://r.789695.n4.nabble.com/Orthogonal-contrasts-in-mixed-effect-models-tp4361007p4361007.html Sent from the R help mailing list archive at Nabble.com.